Manufacturers of photographic film have placed a bar code along one of the edges of filmstrips to supply information about the film to devices contained within photographic printers. Two bar codes usually appear on every frame of the filmstrip. The device uses the information contained in the bar code to set or adjust various photographic printer parameters to produce better quality prints.
The bar code includes a data track and a clock track. The bar and clock tracks appear as a latent image between the sprocket perforations along one of the edges of the filmstrip. The information contained within the bar code clock track specifies the location of the data bits contained in the data track and help locate the entry and exit codes contained in the data track. Data track information includes: the entry codes; the film product class; the film type; frame number, a reserved data bit and the exit code.
The prior art used a data sensor, an amplifier, an analog-to-digital converter and a microprocessor, that used software to perform logarithmic calculations, to process the data track information. A clock sensor, an analog-to-digital converter, and a microprocessor, that used software to perform calculations, were used to process the clock track information. Prior art analog-to-digital converters were only able to sample each bar of the bar code at a film speed of 18 inches per second three to four times. If the speed of the film was increased, the prior art devices were not able to accurately read the bars of the bar code. Thus, one of the disadvantages of the prior art was that fast film processing speeds could not be used since the bars of the bar code were not able to be accurately read.